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Hard Carbon Aerogels: Superelastic Hard Carbon Nanofiber Aerogels (Adv. Mater. 23/2019)

Advanced Materials 2019年第23期31卷

作者： Zhi‐Long Yu Bing Qin Zhi‐Yuan Ma Jin Huang Si‐Cheng Li Hao‐Yu Zhao Han Li Yin‐Bo Zhu Heng‐An Wu Shu‐Hong Yu Division of Nanomaterials & Chemistry Hefei National Laboratory for Physical Sciences at the Microscale CAS Center for Excellence in Nanoscience Hefei Science Center of CAS Department of Chemistry University of Science and Technology of China Hefei 230026 China CAS Key Laboratory of Mechanical Behavior and Design of Materials Department of Modern Mechanics CAS Center for Excellence in Complex System Mechanics University of Science and Technology of China Hefei 230027 China

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Compact-design, Modeling and simulation of the Internal Permanent Magnet of Magnetically Guided Capsule Endoscope

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Journal of Physics: Conference Series 2022年第1期2187卷

作者： Guanqing Zhang Ruixue Yin Kemin Wang Wenjun Zhang Biomedical Science and Technology Research Center School of Mechatronic Engineering and Automation Shanghai University Shanghai 200444 China Complex and Intelligent System Research Laboratory (CISRL) School of Mechanical and Power Engineering East China University of Science and Technology Shanghai 200237 China Division of Biomedical Engineering University of Saskatchewan Saskatchewan Canada

Miniaturization is a challenge for the magnetically guided capsule endoscope (MGCE), especially considering the multifunction of MGCE. This paper proposes a compact-design of internal permanent magnet (IPM), which contributes to the miniaturization of MGCE. The IPM is a complex of actuator and shell of the MGCE, which frees the occupation of conventional IPM. The IPM is for the first time designed with a streamline shape for good kinematics. A magnetic propulsion model of the proposed IPM is established and a magnetic propulsion simulation based on finite element (FE) and boundary element (BE) analysis for guaranteeing steady locomotion and navigation is conducted. The simulation is validated by comparison of the analytical model. At last, the locomotion modes and navigation of IPM are simulated based on the justified simulation. In conclusion, the compact-design of IPM can guarantee the locomotion and navigation of MGCE, and increase the available inner space of MGCE.

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Comparative study of VSP binning methods for estimating fuel consumptions of LDVs on urban roads

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AIP Conference Proceedings 2019年第1期2066卷

作者： Qi Zhao Qi Chen Guohua Song Lei Yu 1Beijing Key Laboratory of Urban Intelligent Traffic Control Technology North China University of Technology Beijing 100144 China 2MOE Key Laboratory for Urban Transportation Complex System Theory and Technology Beijing Jiaotong University Beijing 100044 China 3College of Science and Technology Texas Southern University Houston Texas 77004 United States

The micro-scale fuel consumption model is a tool commonly used to evaluate the effect of traffic flow conditions on vehicle fuel consumptions, which is an essential step in developing traffic management strategies for saving fuels. In developing any micro-scale fuel consumption model, the Vehicle Specific Power (VSP) binning method has been widely adopted in recent years as a fundamental approach. Existing studies have shown that the high distribution frequency when VSP=0 contributes to high fuel consumptions, so a question quickly emerged about whether VSP=0 should be designed as an independent VSP bin in the VSP binning method. This paper strives to compare different VSP binning methods for Light-Duty Vehicles (LDVs) on urban roads in Beijing in terms of their effects on the estimation of fuel consumptions. After collecting and processing field vehicle activity data and fuel consumption data, three VSP binning methods are proposed for the study. Then, total fuel consumptions and fuel consumption factors are calculated by using the proposed VSP binning methods as well as the second-by-second and average travel speed data. Finally, the estimation accuracy of total fuel consumptions and fuel consumption factors based on the three different VSP binning methods are compared for LDVs on urban roads. The study proves that an independent VSP bin at VSP=0 is indeed necessary, which can improve the estimation accuracy on both total fuel consumptions and fuel consumption factors.

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Comparison of the modified Monod and Droop function combined with Logistic function for describing algae growth

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IOP Conference Series: Earth and Environmental science 2020年第1期612卷

作者： W W Kong S L Huang F F Shi Z J Yang Y B Feng Z Khatoon Key Laboratory of Pollution Processes and Environmental Criteria of the Ministry of Education Tianjin Key Laboratory of Environmental Technology for Complex Trans-Media Pollution Numerical Simulation Group for Water Environment College of Environmental Science and Engineering Nankai University Tianjin 300350 PR China Tianjin Key Laboratory of Clean Energy and Pollution Control School of Energy and Environmental Engineering Hebei University of Technology Tianjin 300401 PR China

Microcystis aeruginosa (M. aeruginosa) are algae found in common freshwater blooms in China, and Dunaliella tertiolecta (D. tertiolecta) are economically important marine algae. Understanding of the microbial growth kinetics plays a significant role in the management of M. aeruginosa's blooms and biodiesel production by D. tertiolecta. This study has shown that the combination of mechanistic models (Logistic and Monod) proved to be efficient in describing relationship between M. aeruginosa growth rates and specific concentrations of total dissolved phosphorus (TDP), orthophosphate (PO43--P), total dissolved nitrogen (TDN) and ammonia (NH4+-N) reasonably with R2=0.28-0.93. Meanwhile, results also show that both PO43--P and NH4+-N are important forms of TDP and TDN in influencing M. aeruginosa growth. It was also noted that the combination of modified Monod and Logistic functions is suitable for describing specific growth rates of D. tertiolecta versus extracellular nitrate concentrations (R2=0.24-0.72). In terms of the combination of Droop and Logistic functions, it was analysed to better explain the relationships between M. aeruginosa specific growth rates and cellular P and N concentrations (R2=0.41-0.86) as compared to the application of Droop function alone. It is also observed that the relationship between D. tertiolecta specific growth rates and intracellular nitrate concentrations also can be well described by the combination of Logistic and Droop functions. In addition, M. aeruginosa growth was affected by less intracellular P concentrations than intracellular N concentrations. In sum, the combination of modified Monod and Logistic functions and the combination of Droop and Logistic functions all can predict algae growth reasonably well, while the combination of Droop and Logistic functions is slightly better. Meanwhile, it is through these two combinations that two sets of better parameters in modified Monod and Droop functions can be respectively obtained t

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Quantifying the Immediate Effects of the COVID-19 Pandemic on Scientists

arXiv

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arXiv 2020年

作者： Myers, Kyle R. Tham, Wei Yang Yin, Yian Cohodes, Nina Thursby, Jerry G. Thursby, Marie C. Schiffer, Peter E. Walsh, Joseph T. Lakhani, Karim R. Wang, Dashun Harvard Business School Harvard University BostonMA United States Laboratory for Innovation Science at Harvard Harvard University BostonMA United States Center for Science of Science and Innovation Northwestern University EvanstonIL United States Northwestern Institute on Complex Systems Northwestern University EvanstonIL United States McCormick School of Engineering Northwestern University EvanstonIL United States Institute for Quantitative Social Science Harvard University BostonMA United States TyGeron Institute NashvilleTN United States Scheller College of Business Georgia Institute of Technology AtlantaGA United States Department of Applied Physics Department of Physics Yale University New HavenCT United States University of Illinois System UrbanaIL United States Kellogg School of Management Northwestern University EvanstonIL United States

The COVID-19 pandemic has undoubtedly disrupted the scientific enterprise, but we lack empirical evidence on the nature and magnitude of these disruptions. Here we report the results of a survey of approximately 4,500 Principal Investigators (PIs) at U.S.- and Europe-based research institutions. Distributed in mid-April 2020, the survey solicited information about how scientists’ work changed from the onset of the pandemic, how their research output might be affected in the near future, and a wide range of individuals’ characteristics. Scientists report a sharp decline in time spent on research on average, but there is substantial heterogeneity with a significant share reporting no change or even increases. Some of this heterogeneity is due to field-specific differences, with laboratory-based fields being the most negatively affected, and some is due to gender, with female scientists reporting larger declines. However, among the individuals’ characteristics examined, the largest disruptions are connected to a usually unobserved dimension: childcare. Reporting a young dependent is associated with declines similar in magnitude to those reported by the laboratory-based fields and can account for a significant fraction of gender differences. Amidst scarce evidence about the role of parenting in scientists’ work, these results highlight the fundamental and heterogeneous ways this pandemic is affecting the scientific workforce, and may have broad relevance for shaping responses to the pandemic’s effect on science and beyond. Copyright © 2020, The Authors. All rights reserved.

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Coupled Pacific Rim megadroughts contributed to the fall of the MingDynasty’s capital in 1644 CE

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science Bulletin 2024年第19期69卷 3106-3114页

作者： Feng Chen Tao Wang Xiaoen Zhao Jan Esper Fredrik Charpentier Ljungqvist Ulf Büntgen Hans W.Linderholm David Meko Hongna Xu Weipeng Yue Shijie Wang Yujiang Yuan Jingyun Zheng Wei Pan Fidel Roig Martín Hadad Mao Hu Jiachang Wei Fahu Chen Yunnan Key Laboratory of International Rivers and Transboundary Eco-Security Institute of International Rivers and Eco-SecurityYunnan UniversityKunming 650504China Southwest United Graduate School Kunming 650504China Climate Change Research Center and Nansen-Zhu International Research Centre Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China Department of Geography Johannes Gutenberg UniversityMainz 55099Germany Global Change Research Institute(CzechGlobe) Czech Academy of SciencesBrno 60300Czech Republic Department of History Stockholm UniversityStockholm 10691Sweden Bolin Centre for Climate Research Stockholm UniversityStockholm 10691Sweden Swedish Collegium for Advanced Study LinneanumUppsala 75238Sweden Department of Geography University of CambridgeCambridge CB23ENUK Department of Geography Faculty of ScienceMasaryk UniversityBrno 61137Czech Republic Swiss Federal Research Institute(WSL) Birmensdorf 8903Switzerland Regional Climate Group Department of Earth SciencesUniversity of GothenburgGothenburg 40530Sweden Laboratory of Tree-Ring Research University of ArizonaTucson AZ 85721USA Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters(CIC FEMD) Nanjing University of Information Science and TechnologyNanjing 210044China Key Laboratory of Tree-ring Physical and Chemical Research Institute of Desert MeteorologyChina Meteorological AdministrationUrumqi 830002China Key Laboratory of Land Surface Pattern and Simulation Institute of Geographical Sciences and Natural Resources ResearchChinese Academy of SciencesBeijing 100101China Key Laboratory of Digital Human Technology R&D and Application of Yunnan Provincial Department of Education Yunnan UniversityKunming 650504China Laboratorio de Dendrocronología e Historia Ambiental IANIGLA-CCT CONICET-Universidad Nacional de CuyoMendoza 5500Argentina Hémera Centro de Observación de La Tierra Escuela de Ingeniería ForestalFacultad de CienciasUniversidad MayorHuechuraba 85

Historical documents provide evidence for regional droughts preceding the political turmoil and fall of Beijing in 1644 CE,when more than 20 million people died in northern China during the late Ming famine ***,the role climate and environmental changes may have played in this pivotal event in Chinese history remains ***,we provide tree-ring evidence of persistent megadroughts from1576 to 1593 CE and from 1628 to 1644 CE in northern China,which coincided with exceptionally cold summers just before the fall of *** analysis reveals that these regional hydroclimatic extremes are part of a series of megadroughts along the Pacific Rim,which not only impacted the ecology and society of monsoonal northern China,but likely also exacerbated external geopolitical and economic *** finding is corroborated by last millennium reanalysis data and numerical climate model simulations revealing internally driven Pacific sea surface temperature variations and the predominance of decadal scale La Ni?a-like conditions to be responsible for precipitation decreases over northern China,as well as extensive monsoon regions in the *** teleconnection patterns provide a mechanistic explanation for reoccurring drought spells during the late Ming Dynasty and the environmental framework fostering the fall of Beijing in 1644 CE,and the subsequent demise of the Ming Dynasty.

关键词： Paleoclimate Beijing Precipitation reconstruction Climate-society interactions Tree rings Ming Dynasty

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CeO 2 quantum dots/LZU1 Z-scheme heterojunction for photocatalytic selective oxidative coupling of benzylamines

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Journal of Rare Earths 2024年

作者： Yezi Hu Rusong Sang Feng Chu Zewen Shen Guixia Zhao Junrong Yue Xiubing Huang MOE Key Laboratory of Resources and Environmental System Optimization College of Environmental Science and Engineering North China Electric Power University Beijing 102206 China State Key Laboratory of Multi Phase Complex System Institute of Process Engineering Chinese Academy of Sciences Beijing 100190 China Beijing Advanced Innovation Center for Materials Genome Engineering Beijing Key Laboratory of Function Materials for Molecule & Structure Construction School of Materials Science and Engineering University of Science and Technology Beijing Beijing 100083 China

Imines play a pivotal role as multifunctional intermediates in pharmaceutical and biological applications, and their selective synthesis under mild conditions has attracted increasing interest. In this study, a covalent-organic frameworks (COFs) modified with CeO 2 quantum dots (QDs) were prepared through a simple chemical reaction using LZU1 COFs and Ce(NO 3 ) 3 ·6H 2 O serving as precursors. The optimized 5CeO 2 QDs@LZU1 decorated with about 3.9 wt% CeO 2 QDs demonstrates excellent performance in the photocatalytic selective oxidative of amines in visible light conditions, achieving nearly 100% benzylamine conversion and over 99% imine selectivity within 6 h, which is significantly superior to that of pure LZU1 and CeO 2 . The remarkable enhancement in activity is mainly attributed to the fact that the interaction between CeO 2 QDs and LZU1 COF in 5CeO 2 QDs@LZU1 improves the visible light response and concurrently promotes the separation efficiency of photogenerated e ‒ and h + pairs. Broad substrate scope also provides a prospect for the industrial synthesis of various imines. Our findings not only expand the application range of COFs by incorporating QDs but also lay the groundwork for their further rational design and optimization.

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Emergent functional neural networks organized by spike timing dependent synaptic plasticity

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BMC Neuroscience 2007年第2期8卷 1-1页

作者： Chang-Woo Shin Seunghwan Kim Asia Pacific Center for Theoretical Physics National Core Research Center for System Biodynamics and Nonlinear and Complex Systems Laboratory Department of Physics Pohang University of Science and Technology San 31 Hyoja-dong Nam-gu Pohang Gyungbuk 790-784 Korea

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Large loss of CO2 in winter observed across the northern permafrost region (vol 9, pg 852, 2019)

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NATURE CLIMATE CHANGE 2019年第12期9卷 1005-1005页

作者： Natali, Susan M. Watts, Jennifer D. Rogers, Brendan M. Potter, Stefano Ludwig, Sarah M. Selbmann, Anne-Katrin Sullivan, Patrick F. Abbott, Benjamin W. Arndt, Kyle A. Birch, Leah Bjorkman, Mats P. Bloom, A. Anthony Celis, Gerardo Christensen, Torben R. Christiansen, Casper T. Commane, Roisin Cooper, Elisabeth J. Crill, Patrick Czimczik, Claudia Davydov, Sergey Du, Jinyang Egan, Jocelyn E. Elberling, Bo Euskirchen, Eugenie S. Friborg, Thomas Genet, Helene Gockede, Mathias Goodrich, Jordan P. Grogan, Paul Helbig, Manuel Jafarov, Elchin E. Jastrow, Julie D. Kalhori, Aram A. M. Kim, Yongwon Kimball, John S. Kutzbach, Lars Lara, Mark J. Larsen, Klaus S. Lee, Bang-Yong Liu, Zhihua Loranty, Michael M. Lund, Magnus Lupascu, Massimo Madani, Nima Malhotra, Avni Matamala, Roser McFarland, Jack McGuire, A. David Michelsen, Anders Minions, Christina Oechel, Walter C. Olefeldt, David Parmentier, Frans-Jan W. Pirk, Norbert Poulter, Ben Quinton, William Rezanezhad, Fereidoun Risk, David Sachs, Torsten Schaefer, Kevin Schmidt, Niels M. Schuur, Edward A. G. Semenchuk, Philipp R. Shaver, Gaius Sonnentag, Oliver Starr, Gregory Treat, Claire C. Waldrop, Mark P. Wang, Yihui Welker, Jeffrey Wille, Christian Xu, Xiaofeng Zhang, Zhen Zhuang, Qianlai Zona, Donatella Woods Hole Research Center Falmouth MA USA University of Bayreuth Bayreuth Germany Environment and Natural Resources Institute University of Alaska Anchorage AK USA Department of Plant and Wildlife Sciences Brigham Young University Provo UT USA Department of Biology San Diego State University San Diego CA USA Department of Earth Sciences University of Gothenburg Göteborg Sweden Jet Propulsion Laboratory California Institute of Technology Pasadena CA USA Center for Ecosystem Science and Society Northern Arizona University Flagstaff AZ USA Department of Bioscience Arctic Research Centre Aarhus University Roskilde Denmark NORCE Norwegian Research Centre Bjerknes Centre for Climate Research Bergen Norway Department of Earth and Environmental Sciences of Lamont-Doherty Earth Observatory Columbia University Palisades NY USA Department of Arctic and Marine Biology Faculty of Biosciences Fisheries and Economics UiT The Arctic University of Norway Tromsø Norway Department of Geological Sciences and Bolin Centre for Climate Research Stockholm University Stockholm Sweden Earth System Science University of California Irvine CA USA Northeast Science Station Pacific Geographical Institute Cherskii Russia Numerical Terradynamic Simulation Group W.A. Franke College of Forestry & Conservation University of Montana Missoula MT USA Department of Earth Sciences Dalhousie University Halifax Nova Scotia Canada Center for Permafrost Department of Geosciences and Natural Resource Management University of Copenhagen Copenhagen Denmark Institute of Arctic Biology University of Alaska Fairbanks Fairbanks AK USA Department of Geosciences and Natural Resource Management University of Copenhagen Copenhagen Denmark Max Planck Institute for Biogeochemistry Jena Germany Scripps Institution of Oceanography University of California San Diego La Jolla CA USA Department of Biology Queen’s University Kingston Ontario Canada School of Geography and Earth Sciences McMa

Recent warming in the Arctic, which has been amplified during the winter1,2,3, greatly enhances microbial decomposition of soil organic matter and subsequent release of carbon dioxide (CO2)4. However, the amount of CO... 详细信息

Recent warming in the Arctic, which has been amplified during the winter^1,2,3, greatly enhances microbial decomposition of soil organic matter and subsequent release of carbon dioxide (CO₂)⁴. However, the amount of CO₂ released in winter is not known and has not been well represented by ecosystem models or empirically based estimates^5,6. Here we synthesize regional in situ observations of CO₂ flux from Arctic and boreal soils to assess current and future winter carbon losses from the northern permafrost domain. We estimate a contemporary loss of 1,662 TgC per year from the permafrost region during the winter season (October-April). This loss is greater than the average growing season carbon uptake for this region estimated from process models (−1,032 TgC per year). Extending model predictions to warmer conditions up to 2100 indicates that winter CO₂ emissions will increase 17% under a moderate mitigation scenario—Representative Concentration Pathway 4.5—and 41% under business-as-usual emissions scenario—Representative Concentration Pathway 8.5. Our results provide a baseline for winter CO₂ emissions from northern terrestrial regions and indicate that enhanced soil CO₂ loss due to winter warming may offset growing season carbon uptake under future climatic conditions.

关键词： Climate sciences Ecology Ecosystem ecology

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PDϑControl Strategy for a Fractional-Order Chaotic Financial Model

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complexity 2019年第1期2019卷

作者： Changjin Xu Maoxin Liao Peiluan Li Qimei Xiao Shuai Yuan Guizhou Key Laboratory of Economics System Simulation Guizhou University of Finance and Economics Guiyang 550004 *** School of Mathematics and Physics University of South China Hengyang 421001 *** School of Mathematics and Statistics Henan University of Science and Technology Luoyang 471023 *** Hunan Provincial Key Laboratory of Mathematical Modeling and Analysis in Engineering Changsha University of Science and Technology Changsha 410114 *** School of Mathematics and Statistics Central South University Changsha 410083 ***

In this article, based on the previous works, a new fractional-order financial model is put up. The chaotic behavior of the fractional-order financial model is suppressed by designing an appropriate P D ϑ controller. By choosing the delay as the bifurcation parameter, we establish the sufficient condition to guarantee the stability and the existence of Hopf bifurcation of fractional-order financial model. Also, the influence of the delay and the fractional order on the stability and the existence of Hopf bifurcation of fractional-order financial model is revealed. An example is given to confirm the effectiveness of the analysis results. The main findings of this article play an important role in maintaining economic stability.

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